Sharing your story is key.
As an ex-Republican I attended a town meeting for our local, congressman (D). The hall was packed with young, energetic and focused on Medicare for All. After the meeting, I had a short conversation in the parking lot with a small group.
I noted that I was on Medicare, but against Medicare for All. When challenged, I replied that, from my position as a military veteran, Medicare for All sounded too much like VA Care for All and there was no way I could support that.
They didn't know how to answer that and said they would have to look into it. That was exactly the answer I wanted.